基于NSGA-Ⅱ的并联混合动力客车传动比优化

Transmission Ratio Optimization for a Parallel Hybrid Electric Bus Based on NSGA-ⅡGenetic Algorithm

对装有5挡变速器的并联式混合动力客车进行了动力系传动比的经济性和动力性双目标参数优化设计。基于并联式混合动力客车的电辅助式控制策略,利用AVL-Cruise建立其整车仿真模型。以该客车的动力性及单次充满电的续驶里程为约束条件,以最小等效百公里耗气量和0~50 km/h的加速时间为优化目标,在Isight软件平台上设计多目标优化模型。采用非支配排序遗传算法（NSGA-Ⅱ）对变速器传动比及主传动比进行多目标优化,并对优化结果进行了并联式混合动力客车性能仿真。与优化前相比,在保证动力性的基础上,其等效百公里耗气量下降了8.4%,0~50 km/h的加速时间缩短了1.1%。

Based on the dynamical and economical performance of the parallel hybrid electric bus with 5 speeds transmission,the bi- objective optimization was designed for the ratio of power train system. Depending on the parallel electric auxiliary control strategy in a parallel hybrid electric bus,a vehicle dynamic simulation model was built with the software AVL Cruise. Aiming at the minimization of equivalent fuel consumption and acceleration time from 0 to 50 km / h,the gear ratio and final drive ratio were chosen as optimization variables,while the dynamical performance and driving range with a full battery were constraints.Based on the software Isight,multi- objective optimization model was built. The elitist non- dominated sorting genetic optimization algorithm（ NSGA- Ⅱ） was applied to achieve the multi- objective optimization of the gear ratio and final drive ratio; and based on the Pareto optimal solution,the dynamic simulation of the parallel hybrid electric bus was achieved. Finally,compared with the original parallel hybrid electric bus,equivalent fuel consumption was decreased by 8. 4% and acceleration time was decreased by 1. 1%.